Design, synthesis, and evaluation of some biologically active molecules /
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| Other Authors: | , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1991.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy |
| Abstract: | Chapter II describes the mechanistic effects of organic solvents. By using amide and ester substrates Suc-Ala-Ala-Pro-Phe-X (X = pNA and SBzl), energy diagrams were constructed to understand the effects of both organic solvent and chemical modification. The results showed that organic solvent modification provides more efficient catalysts for aminolysis. The effect of organic solvent on the partitioning indicated that the addition of organic solvents makes the aminolysis of acyl enzymes a more favorable route than the hydrolysis. The P2 site specificity of subtilisin was also investigated and it was shown that the S2 binding site in proteases was well preserved with 50% DMF as cosolvent. Chapter III describes the development of several competitive inhibitors and mechanism-based inactivators of subtilisin BPN'. Various methyl arylalkane sulfonates were prepared and shown to be either competitive inhibitors or selective methylating reagents for the ε2-N of the active-site His. The second-order rate constant of inactivation and the K[i] of the enzyme reacting with the methylating reagents and other inactivators were determined. The methylated enzyme was purified to homogeneity and the kinetic constants for the enzyme-catalyzed ester and amide hydrolyses were determined. The methylated enzyme lost most of the amidase activity while the esterase activity was still significant and useful for peptide synthesis via aminolysis. Chapter IV describes the evaluation and modeling studies of some azasugars and their diasteromerically pure tertiary amine oxides, as well as 5-thioglucose and its sulfoxide derivatives as glycosidase inhibitors. It was found that all the synthetic azasugars and 5-thioglucose were strong inhibitors, but oxidation of the ring heteroatom weakened the inhibition. With the aid of molecular modeling and inhibition analysis a structure-K[i] relation of inhibitors was established which provides useful information for the design of new glycosidase inhibitors. Chapter V describes the characterization of two stable subtilisin mutants, subtilisin 8397 and 8399. Mutant 8397 has a half-life of 350 h in DMF and 1,600 h in aqueous solution at pH 8.4, 25 °C. Kinetic and inhibition analyses of the enzymes indicate that the mutant and wild type enzymes have similar substrate specificities and catalytic efficiencies. Application of the enzyme to organic synthesis in DMF-H2O was illustrated by the enantioselective hydrolysis of unnatural amino acid esters and synthesis of peptides. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Chemistry." |
| Physical Description: | xvii, 136 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |